Shoe stiffener manufacture



Patented Nov, l, 1932 Human 51mm JOSEPH M. LURIE, OF BROOKLIN'E, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO ARDEN BOX TOE COMPANY, OF WATERTOWN, MASSACHUSETTS, A COR- PORATION OF MASSACHUSETTS SHOE STIFFENER MANUFACTURE Ho Drawing.

This invention relates to shoe stiffener manufacture, according to which. fibrous sheet material is treated with compositions to produce shoe stiffener material from which shoe stifiener arts, such as box toe blanks, may be out. I involves both the process of manufacture and the article or articles resulting therefrom.

Various stiffening compositions have heretofore been used for the impregnation of fibrous sheet material from which shoe stillenerparts were to be cut. One composition heretofore used consists of a solution of a cellulose ester, such as nitrocellulose, in a-suitable solvent. A suitable fibrous foundation has been impregnated with the composition, whereupon the impregnated foundation has been dried to remove the solvent and the dried, impregnated product cut into shoe stiffener parts, such as box toe blanks. A. serious objection to such prior art practice lies in the excessive cost of the solvent and the difiiculty and expense incident to solvent recovery operations, when solvent recovery is carried out. Again, such practice is accompanied by serious fire and explosion hazard, as the combustibility of a cellulose ester, such as nitrocellulose, is aggravated by the high inflammability of the volatile solvents used therewith and the fire and explosion hazard arising from the presence of solvent fumes in the facory.

In accordance with the present invention, the foregoin difficulties are overcome by using a sti ening ,composition comprising a pulverulent cellulose ester anda suitable binder, preferably in the form of anaqueous paste, which after the drying of the composition on or in a suitable foundation coated or impregnated therewith, serves to bond the particles of ester to the foundation so that they are not readily disassociated as dust from the foundation and lost durin handling, cutting, skiving, or the like. arious binding agents, such as starch, casein, sodium silicate, glue, may be employed, but it is preferable to use a water-dispersed binder which is capable of being gelatinized-or softened by the solvents of the ester, as this permits rapid and uniform treatment of the shoe stiffener Application filed; March 12, 1930. Serial No. 435,359.

part with a solvent for the ester, to condition it for the moulding operation. Thus, for example, where box toe blanks are the shoe stifiener parts, it is necessary that they be rendered limp or mouldable prior to the pulling over and lasting operations. By using a binder which may be gelatinized or softened along with the cellulose ester, by asolvent of the celluloid ester, it is easy to effect a rapid and uniform impregnation of the blank with a solvent to condition it for such operations. Rosin soap or size containing more or less free rosin, such as used for papermaking, is an example of abinding material which is dispersed in water and which may be softened or gelatinized by the solvents of the cellulose ester,

but aqueous rubber dispersions may also be used to advantage, particularly when the solvent employed for conditioning the shoe stifiener part is one which effects plasticization of the rubber as well as of the cellulose ester.

While the present invention comprehends the use of cellulose ester such as the nitrate and the acetate in fibrous condition as the raw material for the preparation of the powdered ester I prefer to use celluloid or ,film scrap, and more particularly that variety known as composite hard scrap as a raw material. Such a scrap is available as trimmings or fairly large pieces from the manufacture of toilet ware, hair ornaments, picture frames, and the like, and is far less expensive than the ester in fibrous. or unplasticized condition. Such celluloid scrap may be reduced to a powder expediently and economically by the use of a so-called hammer mill, water being fed through the mill while crushing of the scrap is being effected, so as to avoid fire and explosion hazard and to produce an aqueous suspension of the powder for mixing with the binder. If desired, other suitable grinding, impact or crushing machines may be used for comminuting the celluloid or film scrap in the presence of water.

While various examples of procedure fall- 95 ing within the purview of the present invention are possible, the following are typical procedures which will enable those skilled in the art to practise the present invention in a manner to produce eminently satisfactory scribed is pulverized in a hammer mill in the presence of suflicient water to prevent rise of temperature or possibility of ignition, under which conditions an aqueous. suspension of about solids content is produced. The

aqueous suspension is passed through, say,

a LO-mesh screen to separate out coarse part1- cles, whereupon the suspension is delivered into a container and permitted to stand until the pulverized material settles out and a substantially clear, supernatant layer of water is produced. The water layer is decanted from the mud or sludge of pulverized material, which has a solids content of about 50% and is of a thin, paste-like consistency.

When rosin size or soap of about 50% solids content is used as the binding material, 4 parts by weight of celluloid sludge of 50% solids content is mixed with one part of the rosin size, to produce a physically homo-.

geneous composition. This composition is of a fairly stiff, paste-like consistency, and may be used assuch for the treatment of a suitof shoe st-iifener material. When an aqueous rubber dispersion is used as the binding medium, about 10 parts by weight of the celluloid sludge of about 50% solids content is mixed with 2 parts of latex of, say, about 35% solids content,'to produce a paste of a consistency not unlike that produced when rosin size is used as the binding medium. If desired, both rosin size and latex may be used as the binding media, in which case 20 parts by weight of the celluloid sludge of about 50% solids content is mixed with 5 parts of rosin size of 50% solids content and 1 part of latex of 35% solids content, to produce a paste of a consistency comparable to that obtained when either of the binding media is used alone. The use of rosin size is advantageous, in that not only is it readily softenable by a solvent of the celluloid, but it is inexpensive as compared with latex. It is preferable, however, touse some latex along with the rosin size, as this efl'ects an elastic bond between the celluloid particles and between the particlesand the foundation, and accordingly improves the flexing qualities of the resulting shoe stiffener material. If desired, a small amount of starch paste may be used along with the rosin size and latex, as starch paste is even less expensive than the rosin size and at the same time constitutes an excellent bonding agent. It cannot, however, be used advantageously alon'e, owing to the fact that the solvents for the celluloid do not effect its softening or plasticization.

Any one of the stiffening compositions hereinbefore described may be used for the treatment of a suitablefibrous foundation to produce shoestifi'ening material. Thus, the composition may be spread on the surface of a fabric or may be squeezed thereinto to effect impregnation of the fabric, whereupon the fabric may be dried and cut into shoe stiffener blanks such as box toes, which, as hereinbefore stated, are quickly and uniformly permeable throughout to suitable solvents. This highly desirable property of quick and uniform permeability arises from the fact that the stiffener blanks carry the ester particles so that they are exposed to make direct contact with the solvent. When Isay that the ester particles are exposed to make direct contact with the 'solvent,.I mean that the blanks are not masked on their surfaces with an impervious film or layer of material which prevents or seriously retards an influx of solvent into and throughout the blanks to bring about a gelatinization of substantially all of the cellulose ester particles and thereby a transformation of the blanks into the desired limp and mouldable condition, as hereinbefore described, When the blanks are treated with suitable celluloid solvents such as acetone, ethyl acetate, or suitable solvent mixtures such as a mixture of diacetone alcohol and denatured alcohol or methanol,

they become limp or plastic, in which condition they may be assembled with the shoe uppers prior to the pulling-over and lasting operations. After assembling with the shoe and the removal of the solvent from the shaped blank, the blank acquires the desred qualities of stiffness, flexibility and resiliency. The treatment of the blanks with solvent may be effected at the shoe factory, but it is preferable to treat them at the shoe stiffener factory and thento pack them in hermetically sealed containers, so that the solvent and solvent fumes may have ample opportunity to act upon the blanks uniformly and completely, so that they reach the shoe factory in condition for immediate use.

The aqueous rubber dispersion employed in the foregoing examples may be a natural dispersion such as latex, or an artificial dispersion of crude or reclaimed rubber. If desired, a so-called vulcanized latex, such as known on the market as vultex, may be used. These dispersions may be used at a solids content of natural latex, i. e., at about 35% solids content, but so-called concentrated latices of much higher solids content may be employed, if the water content of the other raw materials, for instance, the aqueous sludge of celluloid, is increased to offset the reduced water content of the concentrated latex. Fabrics of fine or coarse weave may be used as the fibrous foundation, cotton fabric of comparatively fine weave and socalled laundry cloths which have a coarse weave, being satisfactory. Other porous fibrous foundations, including knitted fabrics, flannels,'or'felt, made either on machinery of the textile or papermaking type,

lions hereinbefore described are preferably made and used in paste form, since when they are in this condition, a single spreading or impregnating treatment suffices to associatesufiicie-nt solids with the fibrous foundation to render it suitable for use as shoe stifl'ener material-. The composition may, however,

in certain instances, be used at lower solids content. I have herein used the term waterdlspersed binder m'a comprehensive Sense to include binders which are dissolved in dispersed rubber, said stiffener being quickly permeable throughout to celluloid solvents and said celluloid particles being exposed to make direct contact with said solvents to induce said permeability.

2. A shoe stiffener comprising a fibrous foundation carrying pulverized celluloid bonded thereto by rosin size, said stiffener being quickly permeable throughout to cellu loid solvents and said celluloid particles being exposed to make direct contact with said solvents to induce said permeability. I

3. A shoe stiffener comprising a fibrous foundation carrying pulverized celluloid bonded thereto by dried, water-dispersed rubher, said stiffener being quickly permeable throughout to celluloid solvents and said cel luloid particles being exposed to make direct V contact with said solvents to induce said permeability.

4. A process which comprises treating a fibrous foundation with an aqueous stiffening composition comprising powdered celluloid and a water-dispersed binding agent, drying the treated foundation to bond the particles of celluloid to the foundation and to impart to said foundation the property of quick and substantially uniform permeability to celluloid solvents, cutting the dried product into shoe stiffener parts, and treating the parts with a solvent of the celluloid to condition them for assembly with'shoe uppers.

5. A process which comprises treating a fibrous foundation with an aqueous stiffening composition comprising powdered celluloid I and a water-dispersed binding agent capable of being gelatinized by a solvent of the celluloid, drying the treated foundation to'bond, the particles of ester to the foundation and to impart to said foundation the property of quick and substantially uniform permeability to cellulose ester solvents, cutting the dried product into shoe stiffener parts, treating the parts with a solvent of the celluloid of gelatinizeboth the celluloid and binding agent,

and assembling the parts thus treated with shoe uppers.

6. A process which comprises treating a fibrous foundation with an aqueous stiffening I composition comprising a powdered cellulose ester and a water-dispersed binding agent,

drying the treated foundation to bond theparticles of cellulose ester to the foundation and to impart tosaid foundation the property of quick and substantially uniform permeability to cellulose ester solvents, cutting the dried product into shoe stiffener parts, and treating the parts with a solvent of the cellulose ester to condition them for assembly with shoe uppers.

7 A process which comprises treating a fibrous foundation with an aqueous stiffening composition comprising a powdered cellulose ester and arwater-dispersed binding agent capable of'being gelatinized by' a solvent of the cellulose ester, drying the treated foundation to bond the particles of ester to the foundation and to impart to said foundation" the property of quick and substantially uniform permeability to cellulose estersolvents, I

cutting the dried product into shoe stiffener parts, treating the parts with a solvent of the cellulose ester to gelatinize both the cellulose ester and binding agent, and assembling the parts thus treated with shoe uppers.

In testimony whereof I have aflixed my sig- JOSEPH M. LURIE;

' nature. 

